Audi A4, S4

since 2000 of release

Repair and car operation

Checks of a control system by ignition and injection

Address also to the Section Diagnostics of malfunctions.

Components of a control system are very reliable. Malfunctions are, as a rule, connected with unreliability or pollution of contacts. Breakdowns of high-voltage wires arise because of pollution, humidity or isolation damage, instead of because of malfunction a system component more often. Before drawing a conclusion on malfunction of any component, check its conducting.

To check operability of a high-voltage wire, having removed it from a candle and having approached to an engine surface (watching spark existence), it is impossible. You risk not only to receive blow a current, but also to damage the control unit or the ignition coil. If the engine works unstably, never remove tips of wires from candles for definition of the faulty.

Described below check it is necessary to carry out, if malfunction is obvious (starter refusal, admissions of ignition, etc.). Some malfunctions are less obvious and can not be shown because the control system of the engine was switched in the emergency operation ignoring signals of separate sensors and using. This sort of malfunctions are shown in increase of fuel consumption, instability of turns of idling, loss of capacity, a detonation etc. If you found similar symptoms, address on HUNDRED.

The engine is not started

Keep in mind that at failure of the anti-theft device you cannot start the engine. Disconnect the device (address to Head Governing bodies and receptions of safe operation).

If the engine is not turned at inclusion of a starter or turned very slowly, check a starter and the storage battery. Attach the voltmeter to plugs of the battery and measure tension at a provorachivaniye of the crankshaft of the engine by a starter. Do not include a starter more than for 10 seconds. If the voltmeter shows 9.5 Volts and less, be convinced of serviceability of the accumulator, a starter and charging system (address to the Section of System of a charging and start).

If at starter inclusion the engine rotates with usual speed, but is not started, check all high-voltage components of system of ignition.

Following instructions of the manufacturer, connect a stroboscope and turn the engine crankshaft a starter. If the lamp on a stroboscope lights up, tension arrives on spark plugs. Be convinced of serviceability of candles. If the lamp is not lit, check high-voltage wires (address to the Section Check and replacement of spark plugs. Check of a condition of high-voltage wires).

If the spark is not present, be convinced of serviceability of the coil of ignition (or replace the coil on obviously serviceable or check resistance of windings). If malfunction is not found, look for it in other place. If after coil replacement the engine started to be started — malfunction is found. Do not hurry to throw out the coil and to buy the new. Be convinced of reliability of accession of conducting to the coil (the engine could not be started because of the oxidized contact).

If the coil as it should be, it is faulty, possibly, the powerful buffer target cascade being a component of the control unit of the engine, one of sensors of a control system of the engine or the accompanying knot. In this case in memory of the control unit the code of malfunction which it is possible to consider from memory should be written down.

It is possible to consider codes of malfunctions by means of the special equipment.

Ignition admissions

The reason of admissions of ignition is unreliable contact of conducting to plugs of the coil of ignition or any sensor more often.

Switch off ignition and be convinced of reliability of connection of all sockets of system of ignition.

Check high-voltage wires. Be convinced that they are reliably fixed in points of promezhutochnykhkrepleniye and do not adjoin to metal parts of the engine. If the wire concerns some metal and it damaged isolation, at operation of the engine the spark will be submitted not on a candle, and on weight. At detection even insignificant damage of isolation at least one wire replace all set.

To be convinced of full operability of wires it is possible, having temporarily replaced them with the obviously serviceable.

At replacement of wires change them on one. It you will avoid risk of the wrong connection. Do not damage a wire at installation.

If high-voltage wires are completely serviceable, the reason of emergence of admissions of ignition is, most likely, the coil of ignition or any spark plug. Establish a new set of candles (address to the Section Check and replacement of spark plugs. Check of a condition of high-voltage wires) or check the coil. The faulty or dirty sensor of position of the crankshaft (address to the Section Functioning of a control system and injection of the petrol engine) can be the reason of emergence of admissions of ignition.

If check of aforementioned knots did not lead to improvement of operation of the engine, consider codes of malfunctions from memory of the control unit (address to the Section the Controller of interface of the personal computer with onboard system of self-diagnostics of OBD II according to protocols of the SAE standards (PWM and VPW) and to ISO 9141-2 and Specifications).